Scanners and copiers are commonly-used information capture and processing devices. A scanner is a device that optically scans an object such as an image, printed text, handwriting, and converts the object to a digital image. A copier duplicates information on a paper onto another one. Commonly used in offices are variations of the desktop flatbed device where the document is placed on a glass window for scanning. Portable scanners and copiers have been proposed as well. Modern scanners and copiers typically use charge-coupled devices (CCDs) or contact image sensor (CIS s) as image sensors. Traditionally, the scanners produce two-dimensional images of objects that are usually flat. Three-dimensional (3D) scanners may scan volumetric objects and generate their 3D models.
In operation of a scanner, a lid covers the object in order to provide a uniform background that the scanner software can use as a reference point for determining the size of the document being scanned. A light source is used to illuminate the document. A scan head may be composed of mirrors, lens, filter, and CCD array. The scan head is moved slowly across the object by a belt that is attached to a stepper motor. The image of the object is captured on a line-by-line basis and reflected by one mirror to another. In some scanners, there are only two minors while others use a three mirror approach. Each minor is slightly curved to focus the image it reflects onto a smaller surface. The last mirror reflects the image onto a lens which in turn focuses the image through a filter on the CCD array. Copiers work in a similar way to duplicate content on a paper onto another paper.